continuously variable transmission (cvt) a timeline of cvt innovation 1490 - da vinci sketches a...
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Continuously Variable Transmission (CVT)
A Timeline of CVT Innovation•1490 - da Vinci sketches a stepless continuously variable transmission •1886 - first toroidal CVT patent filed •1935 - Adiel Dodge receives U.S. patent for toroidal CVT •1939 - fully automatic transmission based on planetary gear system introduced •1958 - Daf (of The Netherlands) produces a CVT in a car •1989 - Subaru Justy GL is the first U.S.-sold production automobile to offer a CVT •2002 - Saturn Vue with a CVT debuts; first Saturn to offer CVT technology •2004 - Ford begins offering a CVT
Basics of Transmission
• The job of the transmission is to change the speed ratio between the engine and the wheels of an automobile.
• The transmission uses a range of gears -- from low to high -- to make more effective use of the engine's torque as driving conditions change. The gears can be engaged manually or automatically.
Problems in manual & automatic transmission
Benefits of CVT
• Provide engine torque in optimum condition (road loads / drive shaft torque)
• No shift clonk• Transmission ratio can be adjusted
continuously• Improved fuel efficiency• Better acceleration• Eliminates gear hunting especially when
going up a hill
Behavior of CVT
CVT Design
• Pulley based CVT
• Toroidal CVT
• Hydrostatic CVT
Pulley based CVT
Belt Design
Toroidal CVT
CVT Control
Mathematical Model of CVT